Combined electromagnetic and manual operated switch



Nov. 8, 1949 E. P. BUCKTHAL Er AL 2,487,751

COMBINED ELECTROMAGNETIC AND MANUAL; OPERATED SWITCH Filed Nov. 21, 1945 Y we? i Z Patented Nov. 8 1949 r COMBINED ELECTROMAGNETIC AND MANUAL OPERATED SWITCH Elmer P. Buckthal, Brookfield, and Gene Nidifier, Chicago, Ill., assignors to United Air Lines, Inc., Chicago, 111., a corporation of Delaware Application November 21, 1945, Serial No. 629,992

2 Claims. (01. 200 87) er complicated link and lever systems connected to one or more coil springs movable over center by the links and levers. Something is yet to be desired, therefore, in switches of this type employing a minimum number of simple and rugged parts which may readily be assembled and which provide reliable operation. Furthermore, in switches of this character heretofore known, the reset mechanism for returning the over-center means to its initial position for deenergization of the electromagnetic means have not been entirely satisfactory.

A c rdin lv. it is a further object of this invention to provide a switch of the character indicated embodying improved over-center means and improved manually operable reset means adapted to be associated with an otherwise standard electromagneticallv operated switch.

In carrying out the invention in one form the electromagnetic switch is provided with an arm pivoted for movement between two positions and with over-center means including a leaf spring extending substantially at right angles to the movable arm in spaced relation to the free end thereof. A short rigid toggle link is disposed between and pivotally engages the arm and the spring so as to be carried over center by a predetermined initial movement of the arm in either direction, thereby to effect snap action of the arm to either of its two positions. Magnetic means energizable to move the arm in one direction so as to carry the toggle link overcenter are provided, together with manually operable means normally positioned so as not to interfere with the movement of the arm by the magnetic means, the manually operable means being movable in either of two directions from its normal central position to carry the toggle link reversely over center and return the arm to its first position after the magnetic means is deenergized. Contact means operable between open and closed circuit positions in response to the movement of the arm are provided for controlling any suitable external circuit.

More particularly, the electromagnetic means for operating the arm comprises a substantially L-shaped frame one leg of which overlies an end of a suitable energizing winding and the other leg of which extends along one side of the winding. Pivoted at the end ofv this other leg is a suitable armature adapted to be moved from one position to another by predetermined energization of the winding, and the operating arm heretofore described extends from this armature for movement thereby. The free end of the arm is disposed adjacent the opposite end of the frame from the armature, and a leaf spring is secured to the frame in face-to-face relation with the frame arm which extends over the end of the winding, the spring having a free end portion which extends beyond the frame in spaced relation to the free end of the arm. Both the free end of the movable arm and the free end portion of the spring are provided with grooves for receiving the opposite ends of a short rigid link having a length somewhat greater than the normal distance between the grooves in the arm and the spring. Movement of the arm in either direction between its extreme positions is effective to carry the link over center relative to a groove in the spring so as to operate the arm with a snap action. The reset means includes a second arm extending from the armature and having a cam portion adjacent its free end. Mounted on the magnet frame and normally resiliently held in a central normal position is a slidable reset member spaced from the reset arm so as to permit movement thereof with the armature and first arm. Suitable projections are provided on the slidable member so that when moved in either direction from its central position it will engage the cam portion of the reset arm and return the overcenter means and the armature to their respective initial positions with a snap action.

For a more complete understanding of the invention reference may now be had to the drawings, in which:

Fig. 1 is a side elevational view of an electromagnetic switch embodying the invention;

Fig. 2 is a side elevational view showing the other side of the electromagnetic switch illustrated in Fig. 1;

Fig. 3 is an end view taken from the armature end of the switch;

Fig. 4 is an end view taken from the opposite end of the switch;

Fig. 5 is a detail perspective view showing a partial assembly comprising the armature, the contact operating and reset arms and the overcenter means of the switch shown in Figs. 1 to 4;

Fig. 6 is a top plan view of the switch, and

Figs. '7 and 8 are side elevational views similar to Figs. 1 and 2, respectively, but showing the switch in its other operative position as" compared I with Figs. 1 and 2.

Referring now to the drawing, the invention is shown as embodied in an electromagnetic switch comprising a substantially L-shaped magnetic frame having a short leg II! which overlies one end of an energizing winding H, the second'legv l2 of the frame extending along one side of the winding ll throughout substantially the length thereof. The winding [is mounted on a. suitable magnetizable core [3 which is secured to and extends from the frame leg [0. As shown, the energizing winding [l is provided with suitable terminals M, M which may be connected in any suitable energizing circuit (not shown) for effecting electromagnetic operation of the switch in the manner. to be hereinaiter described.

Pivotally supported adjacent the free end or.

the frame leg [2 is-an armature l 5 which extends over the end of the core [3 and is adapted to be moved from the. position. shown l andz. to the position shown in Figs. '7 and 8 whenever the winding [1 is. energized to a predetermined degree. Extending firom one side of thearmature [5' throughout. substantially the length of the frame leg [2 is a contact-supporting arm lBi which is provided. with an inturned end. portion 11 (Fig. 5) having a groove l8 formed in the end surface thereof for receiving one end of atogglelink la. The other end of the toggle link [9 is cut. away, as shown, to. provide spaced ears 20', in between. which is disposed the free upper end. of a. nonmagnetic leaf spring 2t formed to provide a groove in, which the link i9 is received. Itwill be apparent that the. ears Zll prevent sidewise movement of the. link 19 and thus-maintain the link in pivotal engagement with the groove l8 and the groove in. the free. endof the spring ll. Associated with the leai spring 2.1. is a. secand nonmagnetic spring member 22 which is shorter than the leaf. spring at, it having been found that a. plurality of leaf spring members provides amore uniform deflection andinsures proper pressure on the toggle it throughout. the travel. thereof. The leaf. springs- 2.! and 22,. as shown. bestv in Figs. 4 and '7, are secured inv face-to-face relation. with the frame leg m by means of a stud 23 which. extends through an elongate slot 22a (Fig. 5) in the. leaf spring 22, a. hole. Zia. in the leaf spring, 2. and. threadedly engages the frame leg to. The slot 220:. permits longitudinal adjustment of. the leaf spring 22 relative to the leaf spring 2! to vary the force exerted on the link. [.9 by the two leaf. springs andinsu-re proper operation oil the arm 16-.

Extending from; the other side of. the armature t5- along the opposite-edge or the frame leg t2, as shown best in Fig. 5 is a reset arm 25'- which is. provided at its free end with a sloping" cam por- 4 tion 25a. Mounted on the upper surface of the frame leg I2 is a plate 26 formed of nonmagnetic material, which plate serves to support the manual reset means and the contact structure to be hereinafter described. Secured to the mounting plate 26 at one side thereof by suitable screws 21 is a U-shaped frame 28, the opposite legs of which are apertured to support in slidable relation a longitudinally slidable reset member 29. Surrounding the reset member 29 between the legs of the frame 28 is a. spring 39 the opposite ends of which bear on the frame legs and a central portion of which engages a groove 3| in the reset member, so that thi spring normally resiliently maintains the slidable member 29 in the central position shown in the drawings and serves to return said member to this position after operation therefrom in either direction.

At one side or the frame 28 a projecting portion of the resent member 29 is cut away, as shown, to provide a notch 32 having oppositely disposed cam surfaces 33 and 34 thereon, adapted selectively to engage the cam portion 25a of the reset arm 25, as will be more fully described hereinafter. Secured to one end of the reset arm 29 is a suitable actuating button or knob 35 which is preferably threaded. thereinto, and it will be observed that the opposite end of the reset mam her ZBhas a threaded bore therein, as indicated by the reference numeral 36, to receive the actuating button 35 it the switch is so mounted'as to call tor reset operation from theoppcsite end. Also mounted on the supporting plate 26 alongside the U-shaped frame 2% and the manual reset mechanism is a conventional con-- tact bank 3? which includes a of normally open contacts 38 and a pair of. normally closed contacts. 39. The contacts are oi thespri-ng type and are mounted between suitable insulating. plates as shown, the left-hand ends or thecontact springs, as viewed in Figs, 1, 6 and 7, pro-- v-iding terminal portions 40 as shown best in Fig. 6.. Depending from the lowermost one of" the normally open contacts38- and from the uppermost one of the normally closed: contacts 39 are suitable operating buttons M and t2, respectively, arranged. as shown. so that on upward movement of the contact button. 4 1 bothpairs of contacts will be operated. from the normal positions shown in- Fig. I to the opposite positions shown in Fig. '7, and it will be observed that the inturn'ecl endportion IT 0f the operating arm [6 is disposed immediately below the operating but;

- ton M so asto engage the same when the arm the arm t6 and the armature t5" in. the positions I shown in Figs. 1- and 2. In. this position, as

shown best in Fig.v 2, the cam portion Z511 (if-the reset arm 25 is out of. the path orl movement of the cam: portions 33 and. M- on the reset member 29.

When. the magnetizing winding I t is energized to a predetermined degree with. thepartsin. the positions shown in. Figs; l and. 2', the armature F5 will be attracted and. will move toward the end of the core I 3, thuscaus-ing the free end of the Hi to move upwardly and carry the toggle link l9 over center relative to its pivot point on the leaf spring 2|. As soon as the link l9 passes its over-center position the spring 2| will quickly move the toggle link and the arm IE to their respective uppermost positions shown in Fig. 7, causing the free end of the arm I 6 to engage the operating button 4| and move the normally closed contacts 39 to the open circuit position shown in Fig. 7, the same movement causing operation of the normally open contacts 38 to the closed circuit position shown in Fig. 7, The toggle link and the leaf spring 2| are effective re- Siliently to maintain the contacts in their operated positions shown in Fig. '7 even though the magnetizing winding II is thereafter deenergized, and the parts are so arranged that only a small movement of the armature I5 is required to carry the toggle link over center. Furthermore, it will be observed that the toggle link will pass over center prior to engagement of the free end of the arm IS with the operating button 4| so as to insure positive snap movement of the contacts.

As shown best in Fig. 8, movement of the armature I5 and the operating arm Hi to the position shown in Fig. 7 causes the cam portion 25a of the reset arm 25 to move upwardly into the groove 32 in the reset member 29. In order to return the contacts and the armature to the initial positions shown in Figs. 1 and 2, it is necessary only to move the reset member 29 longitudinally in either direction, as indicated by the arrows A and B in Fig. 8, so as to cause one or the other of the cam surfaces 33 and 34, respectively, to engage and depress the reset arm 25. As soon as the reset arm 25 has moved downwardly a predetermined amount the toggle link l9, by reason of the corresponding movement of the operating arm IE, will again pass over center, whereupon the leaf spring 2| will operate the arm IS with a snap action to its original position shown in Fig. 1 and permit the contacts 38 and 39 to return to their respective normal positions.

In addition to the stud 23, which secures the leaf springs 2| and 22 to the frame leg In, this frame leg is provided with a pair of mounting studs 44 and 45 which, in conjunction with the stud 23, may be employed to provide a threepoint mounting of the switch on any convenient support. In view of the positive action of the operating arm and contacts in either direction by the over-center means and the action of the overoenter means in resiliently maintaining the arm I6 in either position on operation thereto, the switch may be mounted in any desired position and will afford reliable and positive operation of the contacts. For this reason and because of its small size and light weight, the electromagnetic switches embodying this invention are particularly useful in aircraft installations wherein they may be required to operate in any one of many positions and will withstand various shocks and inertia forces.

Although magnetic switches embodying this invention are capable of various uses, they are particularly adapted for use as circuit breakers to interrupt an electric circuit automatically in response to predetermined abnormal circuit conditions. When s0 employed the winding II and the normally closed contacts 39 may be connected in the circuit to be controlled, either in series circuit relation or in any other suitable fashion, so that an overload in the circuit will cause the armature to operate and open the contacts 39 the circuit breaker in response to overload orv other circuit conditions, and it will be understood that either of the two sets of contacts 38 and 39 may be omitted and additional contacts may be added as desired.

While a particular embodiment of the invention has been shown, it will be understood, of course, that the invention is not limited thereto since many modifications may be made, and it is therefore contemplated by the appended claims to cover any and all such modifications as fall within the true spirit and scope of the invention.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. An electromagnetic switch comprising an arm pivoted for movement between two positions, over-center means for selectively operating said arm to either of said positions with a snap action upon a predetermined initial movement of said arm toward either of said positions, magnetic means for moving said arm in one direction to cause said over-center means to 0D- erate said arm to one of said positions, a reset arm mounted for movement with said first mentioned arm, an operating member mounted for longitudinal movement, spring means for resiliently maintaining said member in a central position wherein said member permits movement of said arms to one of said two positions by said magnetic and over-center means, projections on said member for engaging said reset arm when said member is moved longitudinally from said central position in either direction to move said arms away from said one position and cause said over-center means to operate said arms to the other of said positions, and contacts operable between open and closed circuit positions in accordance with said movement of said first arm between said two positions.

2. An electromagnetic switch comprising a substantially L-shaped frame of magnetizable material, a magnetizable core extending from one leg of said frame substantially parallel to the other leg, a magnetizable winding surrounding said core within the legs of said frame, armature means pivoted adjacent the free end of said other leg for movement toward said core upon energization of said winding, a first arm extending from said armature along one side of said other leg and having a groove in the free end surface thereof, a leaf spring secured to said one leg of said frame in face-to-face relation therewith and having a free end portion extending beyond said frame in spaced relation to said free end of said arm. said end portion having a groove therein extending substantially parallel to said groove in said arm within the limits of movement of said end of said arm, a toggle link disposed between said arm and said spring with opposed ends thereof engaging said grooves and maintained therein by the pressure of said spring, whereby a predetermined initial movement of said arm toward either of said positions carries said toggle link over center relative to said groove in said spring for snap action movement of said arm, said armature causing said initial movement of said arm in one direction upon energization of said winding, a second arm extending from said armature and along the side of said other leg opposite from said first arm and movable with said first arm, manually operable means mounted on said other leg of said frame for imparting 

